1. Field of the Invention
This invention relates to height adjustable extensions of in-ground containers for embedded container light supports in airport runways.
2. Background of the Invention
The discussion of the prior art in U.S. Pat. 5,779,349, including the disclosures therein which are prior art to this invention, is incorporated herein by reference as though fully set forth herein. Only so much of the background as will be necessary to set the stage for this invention will be repeated herein.
Conventional lighting fixtures forming part of specialized, set-in-the-ground airport runway lighting systems are mounted on steel or non-metalic containers which for airport runway inset lights, can be one-part or two-part and, sometimes, three-part containers set below the surface of runways, taxiways, and other aircraft ground traffic areas. The bottom sections of the containers are sometimes called shallow light bases. The top sections are called fixed-length extensions and are manufactured in varying lengths and diameters. Flat spacer rings are installed between the extensions and the lighting fixtures for providing further height adjustments. These conventional steel containers, in addition to serving as bases for mounting the lighting fixtures, also serve as transformer housings and junction boxes to bring electrical power to the lighting fixtures.
In the installation of airport runways, the bases of one or two-section containers are embedded in the edges of the pavements at the time of initial construction. The top portions of the lighting fixtures are installed at a close tolerance, slightly above the pavement surface. A typical container which varies in length and diameter is made with an inverted flange at the top end. The flange has a standard set of threaded holes to allow for the runway, taxiway, edge, and other light fixtures to be bolted onto them above the pavement surface, or to allow for the top section of the container to be bolted onto the bottom section, if it is a two-section container. Most existing, conventional containers are two section containers, bolted together at their inverted flanges. The light fixture is bolted onto the top inverted flange of the top section of the two-section container.
Installations of the containers and their lighting fixtures are required on two different occasions: At initial construction, and again on resurfacing or repaving. The process of resurfacing (repaving) buries the flanges on the embedded containers under the pavement. Consequently height adjusting devices with flanges identical to those of the embedded containers are used to raise the container to the new surface level so that lighting fixtures can be installed and aligned above the pavement. In many instances, this requires core-drilling the newly poured or placed pavement down to the now buried top flange of the embedded container.
Depending on the lengths of the runways and taxiways, thousands of these embedded containers are affected, and a wide variety of height adjustments can be involved for differing sizes of embedded containers. In such an adjustment system, fixed-length extensions must be made available in many different lengths to provide the required gross height adjustments. A combination of one or more flat spacer rings, which are manufactured in thicknesses of {fraction (1/16)}, xe2x85x9, xc2xc, and xc2xd inch (1.6, 3.2, 6.3, and 12.7 millimeters, approximately), and other thicknesses, can be used to provide the final height.
Typical fixed-length extensions have one inverted flange on each end to bolt onto the embedded container, and then flat rings are added on top of the fixed-length extension top flange to make finer adjustments before the lighting fixture is bolted onto the flange.
The fixed-length extensions and the flat spacer rings must be individually ordered to the required length. This adjustment system makes conventional installation a difficult and tedious procedure involving (1) field measurement of each individual fixed extension length and flat spacer ring required for every container; (2) record keeping of all those field measurements and locations for ordering and verification; (3) ordering, receiving, and delivering to the field each size according to its location; and (4) frequently having to install more than one flat spacer ring to achieve the required height. The listed complications for the difficult conventional installation procedure are further magnified by the fact that the embedded containers are made in 4 different sizes: 10, 12, 15, and 16 inches (25.4, 30.5, 38.1, and 40.6 centimeters, approximately) in diameter.
Remembering that embedded containers below the pavement surface serve as light fixture bases, transformer housings and junction boxes, and depending on the location of these containers, one appreciates that they are exposed to varying degrees and types of forces applied to them by the aircraft and other vehicular traffic in that location. For example, runway and taxiway centerline light fixtures, and the containers they are bolted onto, are subjected to direct aircraft and other heavy vehicular loading applied to the top flange of the container and forces transmitted down to its walls.
The disclosure of U.S. Pat. No. 5,779,349 teaches the use of mating threaded extension to vary the height of the extensions. The disadvantages of the acme thread feature of the prior art are that it requires an extra manufacturing step (which is eliminated by the instant invention) and reduces the diameter of the in-ground container, whereas the present invention maintains the diameter of the in-ground container in the extensions.
The present invention is a novel extension means for adjusting the height of a previously installed, airport elevated light. The invention is an apparatus for extending the height of an in-ground airport runway lighting system container having a flange on its upper end for reception of a light fixture. The invention has first and second telescoping tubes, each having a wall terminating respectively in a flange at a top end, and a flange at the bottom end. The bottom end flange has bolt holes which register with the flange on the upper end of the in-ground container and the top end is adapted to receiving a lighting fixture. The outer tube has a number of tapped bores. A set screw is inserted into each tapped bore to hold the relative positions of the telescoping tubes until they can be permanently set with concrete, grout, epoxy, or other cementitious substance.
The method of extending the height of an in-ground airport utilizes the following steps:
Provide first and second telescoping tubes as described in the preceding paragraphs. Then position the telescoping tubes at a required height; next tighten the set screws to temporarily preserve the height position; then pour concrete, grout, epoxy, or other cementitious substance around the tubes and allow the concrete, grout, epoxy, or other cementitious substance to set to hold said tubes in place.
The extension is connected to a fixed connecting flange of a conventional, prior art airport elevated light.